Air distribution system for flame tubes of gas turbine engines



March 2, 1954 F M OWNER ETAL 2,670,600

AIR DISTRIB UTION SYSTEM FOR FLAME TUBES 0F GAS TURBINE ENGINES Filed June 15, 1948 6 Sheets-Sheet 1 FM. OW/I/EQ r FaZMAPcA MT March 2, 1954 R OWNER TAL' 2,670,600

' AIR DISTRIB UTION SYSTEM R FLAME TUBES OF GAS TURBINE INES Filed June 15, 1948 I 6 Sheets-Sheet 2 March 2, 1954 OWNER ET AL 2,670,600

AIR DISTRIBUTION SYSTEM FOR FLAME TUBES OF GAS TURBINE ENGINES Filed June 15, 1948 6 Sheets-Sheet s FM OWN/3B zrcz MAZCHAAU ZUZYEMYWMQM ION SYSTEM FOR FLAME TUBES OF GAS TURBINE ENGINES Filed June 15, 1948 6 Sheets-Sheet 4 March 2, 1954 WNE;Q AL 2,670,600

- AIR DISTRIB I 2 88. v u (f0 54 T T '66? 20 I j? 64/ 41 L: w a aa V61 m/w-wrow FM own/5'2 ,a 270K. MdPUHAA/T March 1954 F. M. OWNER ET AL AIR DISTRIBUTION SYSTEM FOR FLAME TUBES OF GAS TURBINE ENGINES 6 Sheets-Sheet 5 Filed June 15, 1948 WVf/VTOZJ FM 0/1 2122 ZGf. MUHANT W U I flme 7 -March 2, 1954 F. M. OWNER ET AL 2,670,600

AIR DISTRIBUTION SYSTEM FOR FLAME TUBES OF GAS TURBINE ENGINES 6 Sheets-Sheet 6 Filed June 15, 1948 FM Ohm/Z2 26717114462454 Zl/Lwm Amy/I89;

Patented Mar. 2, 1954 UNITED STATES PATENT OFFICE AIR DISTRIBUTION SYSTEM FOR FLAME TUBES OF GAS TURBINE ENGINES Application June 15, 1948, serialize. 33,185

Claims priority, application Great Britain June 17, 1947 7 Claims. 1

This invention concerns combustion apparatus for gas-turbine engines of the kind which comprises a pair of concentric'generally cylindrical walls and the flame tubes extend lengthwise of the chamber within the annular space between the walls.

The present invention has for its object to provide an improved construction of combustion chamber of the kind referred to in which a uniform air distribution is obtained for the flame tubes.

According to this invention combustion apparatus for a gas turbine engine of the kind set forth is characterised in that there is provided for each flame tube a baflle which directs the air flowing through the annular chamber uniformly around the tube.

According to another feature of this invention each flame tube, which lies within the combustion chamber, is attached to the outer wall of the. chamber by a single radial arm through which fuel is fed to the burner nozzle.

A practical application of the present invention will now be described, by way of example, with reference to the accompanying drawings whereof:

Figure 1 is a diagrammatic sectional elevation of a gas turbine engine in accordance with the invention,

Figure 2 is a sectional elevation in diagrammatic form of the combustion equipment of the engine of Figure 1,

Figure 3 is a section on the line '33 of-Figure 1,

Figures 4, 5 and 6 are sectional elevations showing certain details of the combustion equipment,

Figure 7 is a partial view in the direction of arrow 1 of Figure 5,

Figure 8 is a view in the direction of the 8 of Figure 7, and

Figure 9 is a partial section on the line 99 of Figure 5.

The engine (see Figure 1) comprises a compressor assembly In, combustion equipment II and a turbine assembly l2. The combustion equipment H lies between the compressor assembly l and the turbine assembly [2 so that compressed air is delivered by assembly lll to equipment H and, in turn, the combustion products are delivered to the turbine assembly l2.

The compressor assembly I0 comprises a lowpressure axial-flow compressor [3 and an axialflow high-pressure compressor [4. The stator case l of compressor I3 is bolted to an annular arrow casing 16 which in turn is bolted to the stator casing ll of the compressor I4. The annular casing conveys compressed air from the compressor [3 to the compressor I4. The compressor [4 delivers to a duct casing l8 which is bolted to the stator casing II. The duct casing conveys air from the compressor assembly It to the combustion equipment I I.

- The combustion equipment ll generally comprises an annular combustion chamber, indicated at l9, within which there is a plurality of flame tubes 20 extending lengthwise of the chamber and spaced around it.

Air from the compressor assembly In is discharged through the annular duct 18 into the annular combustion chamber l9 and the products of combustion are discharged from said chamber into the turbine assembly l2 through an annular opening. The combustion chamber H! has an inner and an outer wall respectively indicated at 2|, 22 (see also Figure 2). The walls 2|, 22 are concentric and extend from the duct casing [B to the guide vane assembly 23 of the turbine assembly l2.

The wall 22 is in three ring-like parts, namely .an inlet part 24, a central part 25 and an outlet part 26. The part 24 is bolted to the casing I8 and the part 26 is bolted to the outer shroud ring 21 of the gas turbine. The central part 25 is bolted to the parts 24 and 26. The outer wall 22' thus connects the casing l8 to the turbine casing 21 and constitutes a stress-bearing member of the engine.

The central part 25 of wall 22 is removable to give access to the flame tubes 20as hereinafter described.

To ensure that the air being supplied to the combustion chamber I9 is uniformly distributed around each flame tube there is provided for each such tube an inner and an outer bafile, respectively indicated at 28, 29 (see Figure 3).

The outer baiile 29, which is arcuate in crosssection lies over the upper part of the outer surface of each flame tube 20 to define therewith an arcuate space 30 extending throughout the length of th tube. The long edges 3| of adjacent baflies 29 lie near to each other so that a complete assembly is built up around the flame tubes.

The inner baffles 28 are formed in a cylindrical element having a plurality of lengthwise extending troughs 32 within each of which the bottom part of a flame tube lies. In this way adjacent long edges of the inner bafiles meet together to form a continuous assembly around the long axis of the combustion chamber. The wall of each trough 32 goes part-way up its fiame tube and defines with it an arcuate space 33 extending over the length of the tube and along which air from the compressor passes.

The bafiles 28, 29 prevent air from coming into contact with walls 2|, 22. Due to the high temperatures of operation in the combustion equipment H it is necessary to cool the walls 2!, 22. To this end the bafiles 28., 219 are respectively spaced from the inner and outer walls 2!, 22 as at 34, 35 and cold air is passed through bleed openings in the baflles to travel lengthwise through the spaces 34, 35 over the walls 2|, 22. This construction also avoids pressure differences on the baiiles.

more clearly shown in Figures 4, 5 and 6 to which reference will now be had. As shown in Figure 4 the inner wall 2! is welded to a flanged ring 36 which is bolted to the casing 48. The bafile 28 is also supported by ring 36, the end of the baflle which is so supported being slit lengthwise at a plurality of points around it to form resilient fingers 51. The latter engage the wall 2| and support the baiile therefrom. The fingers 3! lie in a stepped part of the wall 2i and, in order to provide a smooth entry for the air entering the combustion chamber IS, the baffle 28 carries a plate 38. This plate is spaced by a small amount, as at 39, from the casing l8 and ring 36 so that air may pass from the casing l9 to behind the plate 38 and thence between the fingers 31 into the space 34.

The inner baflle 28 is formed in two ring-like parts (see Figures 2 and 5) which are spaced apart, at 40, so that air travelling along the space 33 passes through the opening 49 into space 34 at the rear of the baiile 28. This air, which is under pressure, passes towards the turbine assembly 42.

Each outer bafile 29 is formed in three parts corresponding to the three parts 24, 25 and '26 of the wall 22. That part M of the bafiie 29 which corresponds to the part 24 of the wall 22 is attached to and carried by said part of the wall. As indicated above, the part 4! is spaced from the part 24. A boss 42 (Figure 4) is bolted to the wall part 24 and passes through the part 41 of bafile 29. The purpose of the boss 42 will be made clear later. An opening'43 is formed between the bafile part 4| and the boss 42 so that air may leak to behind the part 4! to cool the wall part 24. The central part 44 of each baifle 29 (which corresponds to the wall part 25) is attached to said part 25 by a single bolt 45 the purpose of which wil shortly be described. The third part 46 of baflle 29 is associated with part 26 of wall 22 and is supported therefrom by two rows of circumferentially spaced members 4-1. The members 4|, 46 are respectively forked as at 48, 49 each to receive an edge of the central part 44 of each baflle 29.

For inspection and maintenance purposes the bolts 45 are removed from the-central part '25 of the wall 22 and thereafter the said part is unbolted from parts 24 and 26 said slid lengthwise oil the engine. The part 44 of any one, or more, of the baiiles 29 may then be slid lengthwise (towards the right in Figure 6) so that its left hand end leaves the fork 48 whereupon it may be raised outwardly and entirely removed. In this way access may be had to the flame tubes '20.

For assembly the process is reversed. After the 4 central part 25 of the wall 22 is bolted in position to parts 24, 2B the bolt 45 is screwed home to hold the central .part 44 of the baflle 29 against the part 25 of the wall 22 andspaced therefrom.

The part 44 of each batiie 29 has one or more holes 59 (Figure 6) whereby cooling air additional to that leaking through the opening 43 may pass to the space 35 for cooling purposes as above described.

The flame tube 29 is formed in four portions 54, 52-, 53 and 54 (see Figures 1 and 2).

The portion 51 (Figure 4) carries the fuel nozzle 55 and is constituted by a thin-walled casting which is integrally formed with the boss 42. The latter is generally radially disposed of the portion 5! and is bolted to the part 24 of the wall 22. The boss 42 is formed with a gland 56 through which a fuel pipe 51 passes, from the outside combustion chamber, to the nozzle 55. The boss 42 is of streamlined formation in the direction of how of air over the Ifiame tube. A plate '58 prevents access to the interior of the boss 42. The latter constitutes the sole point of attachment of the flame tube 20 to the combustion chamberthe discharge end of the flame tube is, however, supported as hereinafter described.

The casting 5| is formed with a snout '59 having an opening 59 through which primary air passes to around the fuel nozzle 55 in known manner. A swirling motion is imparted to the primary air by a series of vanes 6| which lie around the nozzle 55 and constitute a part. of a spider which supports the nozzle. The vanes G1 are integrally formed during casting.

The portion '52 of the name tube 29 (Figure 6-) is constituted by a. circular, thin sheet-metal member which is suitably attached to the casting El and is formed with openings 62 (Figure 2) through which secondary air passes. The portion 53 is or similar construction and is attached to the portion 52 as by welding. This portion is also formed with holes whereby more of the secondary air may enter the flame tube.

The portion 53 is spigoted into the portion '54 (Figure 5) and has its edge-crimped at 53 so that air passages are formed between these two parts. The spigot joint provides a support. for the portions 5!, 52, 53 of the flame tube whilst-allow ing for lengthwise movements due to expansions and centractions of the flame tube.

The portion '54 is constituted as a breeches piece. The breeches piece has, for each name tube, a circular entry to receive the crim'ped end of portion 53 of the tube and a rectangular discharge end which gives into the turbine assembly 12. At their discharge ends the adjacent sides of adjacent breeches pieces are cut away at -'64 (Figure 5) and welded together along their abutting edges thereby to form a continuous annular exit 65'. The 'breeches pieces '54 are each supported by a plurality of circumferentially spaced top-hat members '66 which are carried by the irmer bafile 28.

The mouth o'fthe annular exit is a short distance from the nozzle guide-vane assembly as at 61, 88. The cooling air passing along the space 35 between the baffle 29 and the wall '22 is discharged through the opening '69 into the stream of combustion products at the nozzle box of the turbine. Similarly, the cooling air flowing along the space '34 between the wall 2| and the panic 2-8 is discharged through the opening 91 into the stream of combustion products. As this air is under pressure itprevents leakage of the combustion productsthrough the openings 61, so

thatanefiective seal is formed at the nozzlebox.

- A metered quantity of air from space 34 may .been'usual .to provide two such firing points and to interconnect the separate combustion chambers for even flame distribution and equalization of pressure. In the present arrangement a simplified construction is permitted. Thus, the interconnections may comprise a stub pipe projecting from the near sides of adjacent flame tubes, the pipes being open-ended with the adjacent ends spaced apart by a small amount.

The outer wall 22 of the combustion chamber I9 is adapted to constitute part of a stressbearing member the other elements of which are the casings l3, it and 18, the conduit l6 and the shroud rin 27. The engine is thus enveloped throughout its length in a tubular load-carrying member. With this arrangement the outer wall 22 will transmit the engine loads from the turbine assembly l2 to the compressor assembly Id and vice versa. When, however, the part 25 of the wall 22 is removed these loads must be so transmitted through another structure.

To this end, the inner wall .2! is bolted to the casing I8, as above described, and is also welded to a ring carried by diaphragm as (Figure 2). The casing It has also bolted to it a diaphragm II and the diaphragms 59, H carry roller bearings 12, 13 whereby the shaft M of the rotor disc 15 of assembly i2 is supported (Figure l).

The diaphragm as engages pistonwise with a ring 16 of the guide-vane assembly 23 (Figure a piston ring seal Ti being provided between the two.

The guide-vane assembly 23 comprises a plurality of guide vanes 18 integrally formed with an inner and outer carrier 19 and 80 respectively. As shown in Figure '3, a group of such guide vanes 18 together with the carriers it and 8D constitute a sector member. The latter are mounted endto-end around the assembly to form 'a complete ring of blades. The sector members are supported by the inner and outer rings of the guidevane assembly 23-so that each is free to expand and contract in an outward radial direction or in a circumferential direction relatively to each other and relatively to the guide-vane rings. To this end, firstly the carrier is of each sector member is held to the inner ring of the assembly 23, being clamped between two annular plates 8!, 82 (Figure 5) which constitute said inner ring. Secondly, the outer carrier 80 is radially spaced from the outer ring 33 of the guide-vane assembly (see Figure 9) and, thirdly, adjacent sector members are spaced apart circumferentially as at 84, Figure 8. Thus, each sector member (with the exceptions about to be mentioned) is supported solely by the inner ring of the guide-vane assembly and projects radially outwardly therefrom in spaced relationship to the adjacent members and the outer ring 33 of the assembly. The carrier 80 of each sector member is slotted as at 85 to receive the head 86 of a pin 81 the shank of which enters a hole in the ring 33.

It is arranged (see Figure 9) that at two diametrically opposite points of the' assembly 23', and'in a horizontal plane, a bolt 88 is screw-r threaded into the outer ring 83 so that its end face 89 enters and accurately fits a radial hole 90 at the bottom of the slot 85. (Figures 7 and 8 show the sector member which is modified by having the hole 90 formed-in it to receive the bolt 88.) When the bolt 88 is screwed home the ring 83 is rigidly connected with the ring 8|, 82 through the associated sector member.

When the part 25 of the wall22 is removed foriinspection, or other purposes, the engine will be at rest so that the loads imposed on the engine shell are due primarily to the weight of the installation. With removal of the wall 25 the loads on the turbine due to its weight are transmitted to the compressor and vice versa through, firstly, the ring 83, secondly the bolts 88, thirdly, the associated sector members in the horizontal plane of the engine, fourthly, the inner ring BI, 82 and, finally, the diaphragm 69 and the inner wall 2| of the combustion apparatus.

Of course, it will be understood that with the arrangement described whilst the part 25 of wall 22 is in position the loads are transmitted partly through the outer and partly through the inner walls 22, 2| respectively of the combustion chamber.

We claim:

1. In combustion apparatus for a gas turbine engine of the kind set forth having inner and outer concentric walls of which the outer wall is removable, flame tubes between said inner and outer walls, an inner baiile member having a separate baffle portion for each flame tube, an outer separate baflie for each flame tube, said inner and outer baffles being spaced from each tube and following the general outline of the flame tube at a substantially constant distance therefrom and means for independently attaching each outer baiile to the outer wall so that, on removal of said outer wall, each outer baflie is iegarately removable to give access to its flame 2. Combustion apparatus according to claim 1 in which there are holes through each baflle to allow part of the air passing over the flame tube to enter and pass along a space between the baffle and the wall which carries the bafiie.

3. Combustion apparatus as claimed in claim 1 in which the outer wall and outer baflie are each in three part lying end to end in the lengthwise direction of the flame tubes and the central part of the wall and baffle is removable to give access to the flame tubes.

4. Combustion apparatus as claimed in claim 3 in which the side parts of an outer baflie are forked to receive the ends of the central part thereof as a sliding fit which permits one end of the central part to be removed prior to the withdrawal of said part.

5. Combustion apparatus as claimed in claim 4 wherein each flame tube is attached to a nonremovable side part of the outer wall of the combustion chamber solely by a single radial arm which in extending from said Wall to the flame tube passes through a non-removable side part of the outer bafiie, the fuel being fed to the burner nozzle through said arm.

6. Combustion apparatus according to claim 5 in which the support arm and the associated end of the flame tube are integrally formed as a casting, said arm being removably attached to a lateral part of the outer wall.

7. Combustion apparatus as claimed in claim 6 7 wherein the burner nozzleis mounted within a, Number group of primary-air swirl vanes which are inte- 2,447,482 grazll y cast with the flame tube and its support. 2,448,561 FRANK MORGAN OWNER; 2,458,497 FRANCIS CHARLES IVOR MARCHANT. 2,547,619 2,563,744 References Cited in the file of this patent 2311,334 STATES PATENTS 25141385 Number Name Date all. M311. 8, Number 2,268,464 Seippel Dec. 30, 1941 9 0 03 2396368 Youngash Mar. 5, 1945 73 01 2,422,213 Smith 1 June 17, 1947 53 ,0 2

Name Date Arnold Aug. 24, 1948 Way F Sept; 7, 1948 Bailey Jan. 11, 1949 Buckland Apr. 3, 1951 Price Aug. 7, 1951 Feilden Oct. 21, 1952 Feilden- 1- Oct. 21, 1952 FOREIGN PATENTS Country Date France Dec. 16, 1946 Great Eritai'n Jung 1 2, 19 16 Great Britain May 14-, 19 17 

